Biology 141

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Biology 141

• The Appendicular Skeleton
• Chapter 8

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INTRODUCTION

• The appendicular skeleton includes
• 2 Pectoral girdles
• Pelvic girdle
• Upper limbs
• Lower limbs
• The appendicular skeleton functions primarily to
  facilitate movement.

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Pectoral Girdle

• Pectoral Girdle scapula clavical
• Clavical S shape,
• articulates with manubrium of the sternum
  medially
• Sternoclavicular joint
• Articulates with the scapula laterally.
• Acromioclavicular joint

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Clavicle

• collar bone
• one of the most frequently broken bones in the
  body
• transmits mechanical force from the upper limb to
  the trunk.

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Clavicle

• Ligaments attached to clavicle stabilize its
  position.

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Pectoral Girdle

• Scapula triangular, flat bone of the shoulder.
  
• Glenoid cavity socket for humerus
• Scapular spine ridge on posterior side dividing
  the superior (supraspinous fossa) from the
  inferior (infraspinous fossa)

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Scapula

• Scapula
• Subscapular fossa anterior concave surface
• Scapular notch on the superior margin, just
  medial to the coracoid process

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Pectoral Girdle

• 3 margins
• medial border vertebral margin
• lateral border axillary margin
• superior border superior margin
• Lateral processes
• acromion process attachment of clavical
  posteriorly
• coracoid process anterior, smaller process, bent
  laterally

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Posterior Surface of Scapula
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UPPER EXTREMITY

• Each upper limb consists of 30 bones
• Humerus - arm
• Ulna - forearm
• Radius - forearm
• Carpals - wrist
• Metacarpals - palm
• Phalanges - fingers

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Upper Extremity

• Joints
• shoulder (glenohumeral),
• Elbow
• Wrist
• Metacarpophalangeal
• Interphalangeal

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Humerus

• The humerus is the longest and largest bone of
  the upper limb.
• Proximal end articulates with the scapula
• Distal end articulates with both the radius and
  ulna.
• Proximal Humerus
• Head anatomical neck
• Greater lesser tubercles for muscle attachments
• Intertubercular sulcus
• Body - shaft
• Deltoid tuberosity V-shaped area

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Humerus

• Distal humerus
• Forms elbow joint with ulna and radius
• Capitulum
• articulates with head of radius
• Trochlea
• articulation with ulna
• Olecranon fossa
• posterior depression for olecranon process of
  ulna
• Medial lateral epicondyles
• attachment of forearm muscles

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Radius

• Radius (on thumb side)
• Proximal
• head articulates with capitulum of humerus
• radial notch of ulna
• tuberosity for muscle attachment
• Distal
• forms wrist joint with scaphoid, lunate
  triquetrum
• Lateral styloid process

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Ulna

• Ulna (on little finger side)
• Proximal
• trochlear notch articulates withhumerus
• olecranon process forms point of elbow
• Distal
• styloid process
• Head
• separated from wrist joint by fibrocartilage disc

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Ulna Radius
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Ulna and Radius
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Carpals, Metacarpal, and Phalanges

• 8 carpal bones - wrist
• 5 metacarpal bones - palm
• 14 phalanges (3 in each finger, two in thumb).

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8 Carpal Bones (wrist)

• Proximal row
• lateral to medial
• scaphoid - boat shaped
• lunate - moon shaped
• triquetrum - 3 corners
• pisiform - pea shaped
• Distal row - lateral to medial
• trapezium - four sided
• trapezoid - four sided
• capitate - large head
• hamate - hooked process

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Metacarpals

• Metacarpals
• 5 total
• 1 proximal to thumb
• Consists of
• Base
• Shaft
• head
• knuckles are the metacarpophalangeal joints

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Phalanges

• Phalanges
• 14 total each is called phalanx
• Each finger consists of 3 bones
• Proximal
• Middle
• distal on each finger
• Thumb only has only proximal and distal bones
• Each bone consists of
• Base
• Shaft
• Head

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Pelvis

• Pelvis includes
• Os coxae
• Sacrum
• coccyx
• Subdivisions
• The greater (false) pelvis
• The lesser (true) pelvis

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PELVIC GIRDLE

• os coxae bones
• provides a strong and stable support the weight
  of the body
• Each os coxa bone is composed of three separate
  bones at birth
• Ilium
• Pubis
• ischium.

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Os Coxa

• Os coxa ossification is complete in the adult
  and the suture lines are not visible.
• front arch os coax join at the symphysis pubis
• fuse at a depression (acetabulum), which forms
  the socket for the hip joint.

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Pelvic Girdle

• Articulate with sacrum and coccyx
• Sacroiliac joint between sacrum and ilium
• Acetabulum circular depression for femur
• Iliac crest from the anterior superior spine to
  the posterior superior spine

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Os Coxa

• Ischium processes
• ischial spine
• ischial tuberosity one sits on this.
• lesser sciatic notch inferior to the ischial
  spine
• greater ischial notch superior to the ischial
  spine
• obturator foramen opening surrounded by the
  ishium and pubis

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Pelvis

• Pelvic brim
• separates false from true pelvis
• false pelvis holds only abdominal organs
• Inlet superior
• Outlet - inferior
• Pelvic axis - path of babies head

• Pelvimetry, the measurement of the size of the
  inlet and the outlet of the birth canal, is
  important during pregnancy

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Female vs. Male

• Pelvic outlet is wider in females.
• Greater sciatic notch is rounder in females,
  shifting the coccyx to widen the pelvic outlet.

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Female vs. Male

• In females, the false pelvis is wider and more
  lateral, widening the pelvic inlet.
• In females, The pubic arch is greater than 90.

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Pelvis

• Male skeleton
• larger and heavier
• larger articular surfaces
• larger muscle attachments
• Female pelvis
• wider shallower
• larger pelvic inlet outlet
• more space in true pelvis
• pubic arch gt90 degrees

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COMPARISON OF PECTORAL AND PELVIC GIRDLES

• The pectoral girdle does not directly articulate
  with the vertebral column the pelvic girdle
  does.
• The pectoral girdle sockets are shallow and
  maximize movement those of the pelvic girdle are
  deeper and allow less movement.
• The structure of the pectoral girdle offers more
  movement than strength the pelvic girdle, more
  strength than movement.

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LOWER LIMB (EXTREMITY)

• Each lower extremity is composed of 30 bones
• Femur -leg
• Tibia-lower leg
• Fibula-lower leg
• Tarsals-ankle
• Metatarsals -arch
• phalanges -toes

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Femur

• The femur or thighbone is the largest, heaviest,
  and strongest bone of the body.
• articulates with the pelvis and the tibia.
• head articulates with acetabulum (attached by
  ligament of head of femur)
• medial lateral condyles articulate with tibia

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Femur

• Head of the femur
• is the obvious rounded projection.
• Neck of the femur
• is the well-defined narrow region next to the
  head of the femur.
• Greater trochanter of the femur
• is the large, roughened area lateral to the head
  where a muscle attaches (gluteus medius).
• Lesser trochanter of the femur
• is a much smaller projection distal to the head
  on the medial side of the bone.  It is also a
  point of muscle

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Femur

• Medial condyle of the femur
• Head-side of bone
• rounded, smooth condyle where the femur
  articulates with the tibia.
• Lateral condyle of the femur - is on the greater
  trochanter side of the bone.

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Patella

• triangular sesamoid bone
• increases leverage of quadriceps femoris tendon
  to maintain the position of the tendon when the
  knee is bent.

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Tibia

• The tibia or shinbone is the larger, medial,
  weight-bearing bone of the leg.
• Tibial tuberosity of the tibia
• prominent, anterior, roughened bump just distal
  to the knee joint. 
• The Quadriceps femoris muscle attaches here.
• Medial malleolus of the tibia
• the projection on the distal end of the tibia. 
  Medial bony projection at the ankle joint.

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Tibia

• Medial condyle of the tibia
• slight depressions on the flat proximal surface
  of the tibia where the femur's condyles
  articulate.
• The medial one is on the same side as the distal
  projection (medial malleolus).
• Lateral condyle of the tibia
• the lateral depression on the flat proximal
  surface of the tibia.

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Fibula

• The fibula is parallel and lateral to the tibia
• Head of the fibula
• proximal end where the fibula attaches to the
  lateral surface of the tibia.  Note- this end is
  not involved in the knee joint
• Lateral malleolus
• distal end, lateral ankle bump.

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Tibia and Fibula
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Tarsals, Metatarsals, and Phalanges

• 7 tarsal bones (ankle)
• share the weight associated with walking
• 5 metatarsal bones (foot arch)
• Fractures of the metatarsals are common among
  dancers, especially ballet dancers.
• 14 phalanges (toes)
• same as that described for the fingers and thumb.

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Tarsals

• Talus
• most proximal, articulates with the tibia. 
• Calcaneus
• largest, most posterior, forms the heel.  The
  Achilles tendon attaches to this bone
• Navicular
• medial, boat-shaped bone
• Cuboid
• cube shaped, lateral to the navicular.
• Cuneiforms first, second and third - 3 small
  stick-like bones. 

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Metatarsus

• Metatarsus
• midregion of the foot
• 5 metatarsals
• 1 is most medial
• Each bone consists of
• Base
• Shaft
• Head

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Phalanges

• Phalanges
• distal portion of the foot
• similar in number and arrangement to the hand
• big toe is hallux

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Arches of the Foot

• Function
• distribute body weight over foot
• yield spring back when weight is lifted
• Longitudinal arches along each side of foot
• Transverse arch across midfoot region
• navicular, cuneiforms bases of metatarsals

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Clinical Problems

• Flatfoot
• weakened ligaments allow bones of medial arch to
  drop
• Clawfoot
• medial arch is too elevated
• Hip fracture
• 1/2 million/year in US
• osteoporosis
• arthroplasty

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DEVELOPMENTAL ANATOMY OF THE SKELETAL SYSTEM

• Bone forms from mesoderm.
• Week 4 skull begins.
• Week 5 extremities develop from limb buds.
• Week 6 hand plates and foot plates.
• Week 8 developed limbs.